http://www.rfc-editor.org/rfc/rfc3140.txt
RFC 3140: Per Hop Behavior Identification Codes, D. Black, S. Brim, B. Carpenter, F. Le Faucheur2001-06-01T23:00:00-00:00This document defines a 16 bit encoding mechanism for the identification of differentiated services Per Hop Behaviors in protocol messages. It replaces RFC 2836. [STANDARDS-TRACK]